FRS event ID 13511 occurs when the FRS database is almost out of disk space.
To correct this situation, free up some disk space on the volume containing the FRS database. If this is not possible, consider moving the database to a larger volume with more free space. For more information about how to move the database to a larger volume, see article 221093, "How to Relocate the NTFRS Jet Database and Log Files" at http://support.microsoft.com/?id=221093.